Effective connectivity alteration according to recurrence in transient global amnesia

Area of Science:

• Neuroscience
• Neuroimaging
• Brain Connectivity

Background:

• Transient global amnesia (TGA) is a neurological condition characterized by sudden, temporary memory loss.
• The underlying neural mechanisms and network alterations in TGA, particularly concerning the hippocampus, require further elucidation.
• Investigating differences between single and recurrent TGA events may offer insights into disease progression and pathogenesis.

Purpose of the Study:

• To evaluate structural covariance network and effective connectivity alterations in the intrahippocampal circuit of TGA patients.
• To compare these network characteristics between single and recurrent TGA events.
• To explore the relationship between network changes and TGA recurrence.

Main Methods:

• Structural covariance network analysis using graph theory on volumetric data from 88 TGA patients and 50 controls.
• Effective connectivity assessment of the intrahippocampal circuit via structural equation modeling.
• Classification of TGA patients into single (N=77) and recurrent (N=11) event groups.

Main Results:

• No significant global structural covariance network differences were found between all TGA patients/single TGA event patients and healthy controls.
• Recurrent TGA patients exhibited significant global structural covariance network alterations, notably a decreased small-worldness index.
• Effective connectivity disruptions were observed from the entorhinal cortex to CA4 in all/single TGA events, and additionally from the subiculum to the fimbria in recurrent TGA events.

Conclusions:

• TGA is associated with significant structural covariance network alterations and intrahippocampal circuit disruption compared to healthy individuals.
• These neural network abnormalities are more pronounced in patients experiencing recurrent amnestic events.
• The findings suggest that altered network connectivity may play a role in the pathogenesis of TGA, especially in recurrent cases.